Modern networks are responsible for interconnecting computing devices operable to exchange data. Data may be exchanged from circuit to circuit on a common circuit board or from circuit board to circuit board along a common backplane, for example, in a computer or server. In some implementations, data may be exchanged over long distances, for example, from a travel agent's computer to an airline server on a cloud network.
Data can be transferred in the form of bits and bytes over a digital or analog media. Data transmit and receive systems enable digital or analog communications and its movement between devices. Analog data transfer typically sends data in the form of analog signals, while digital data transfer converts data into digital bit streams. An analog signal is one which a parameter (e.g., amplitude, phase) that varies smoothly. Video and audio transmissions are often transferred or recorded using analog signals. Digital signals must have a finite set of possible values (e.g. binary on/off).
A phase-locked loop (PLL) is a frequency control circuit that generates an output signal whose phase is related to the phase of an input signal. A frequency oscillator and a phase detector in a feedback loop are often used to form a PLL. Performance parameters about a PLL may include, for example, hold-in range, pull-in range, lock-in range, and loop bandwidth. A duty cycle is the percentage of time a signal is active. It may be determined from the ratio between a pulse duration and the period of a rectangular waveform.